Dead people are involved? Yes, but may misleadMediums? No Communicating with the dead? rephrase, please, unless you really want a "yope", here. Has someone been dead for 500 years? YES. More than that, as a matter of fact...

Someone was dead for 500 years, Yes and then something relevant happened? Yes, but it's not quite that simple...

Communications from dead people? to dead people? among dead people? No, none of these, all the communication takes place between live people...Corpses involved? NoIs information being deduced from examining 500-year-old corpses? No

Hmmm...I'm a bit stuck on this one, but with work so busy, perhaps that's a good thing so that I'm not that distracted. Nonetheless, time to tackle this puzzle from another angle. I feared that I had been abandoned; thanks for coming back. I hope that it's good-busy and not bad-busy. And another angle would be good...

The two people directly involved: How old are they? Exact ages are unknown, but one is well over 600 years old, possibly over 700, the second is somewhat younger, but still at least a bit over 500 at the time of the puzzle. Relevant? Extremely! I wondered when someone would break out the SBQ's...

What gender are they? Both are male. Relevant? Yes.

Are their professions relevant? Yes. Relationship to each other? Yes!

The one indirectly involved person: same set of questions, please Male, Profession is relevant; Relationship to the other men is relevant; Age at death is 43, somewhat relevant.

Unfortunately, it's a bad busy....have been pulling 12-13 hour workdays for the past 3 weeks, and there is still 2 more weeks to go! Oh, ick. You have my sympathy. Would a virtual backrub help?

500+ and 700+ year olds? Yeppers.And they are still alive? at the time of the puzzle, yes... Are they human? Yes. Immortal? Yope. How they got that way is relevant. Brothers? No. Ancestor/Descendant?No. Undead? No.

The dead man -- did he die of natural causes? No. Murdered? Accidental death? He died in battle, so his death was not accidental, but not murder.

The quest for the Holy Grail relevant? If I wanted to send you off on a wild goose chase, I could find a very tenous, extremely tortured connection and say 'yes-ish.' But I don't want to do that, so: No, not the Grail.

If I wanted to send you off on a wild goose chase, I could find a very tenous, extremely tortured connection and say 'yes-ish.' But I don't want to do that, so: No, not the Grail.I suppose I should be grateful for small mercies.

The nobility: a king? Duke? Count? Baron? Marquis? Lord? Is his exact rank even relevant?

If the 3rd man didn't die, would the other other two still have achieved their 'immortality'?

The timing of the 3rd man's death: before the younger of the 'immortals' was born? after the younger of the 'immortals' was born? before the older one? after the older one?

At the time of the knight's death, were any of those two people 'immortal'?

These two 'immortals' -- can they be killed? If yes to the last question: assuming that they don't get killed, would they be expected to live forever?

The nobility: a king? Duke? Count? This one. Baron? Marquis? Lord? Is his exact rank even relevant? YES. He's most often referred to by his title, not his name.

also: BLOOPER ALERT: He's two thousand years old, which is substantially more than 700+

If the 3rd man didn't die, would the other other two still have achieved their 'immortality'? Yes. His death had no bearing on their immortality.

The timing of the 3rd man's death: before the younger of the 'immortals' was born? Yes.after the younger of the 'immortals' was born? No.before the older one? No.after the older one? Yes. See Blooper above.

At the time of the knight's death, were any of those two people 'immortal'? Yes. The older of them already was, and had been for quite some time.

These two 'immortals' -- can they be killed? As I understand the subject, Yes. Their immortality is not invulnerability.If yes to the last question: assuming that they don't get killed, would they be expected to live forever? They would live as long as they wanted to, but this area could stand some more exploration...